Machines such as, for example, internal combustion engines, transmissions, and hydraulic tools often have fluid systems associated therewith. These fluid systems can include, among others, a lubrication system, a working fluid system, a cooling system, and a fueling system. The fluid levels of each of these systems may require period inspection and replenishment. One way to inspect the fluid level is through the use of a fluid level gauge, also known as a dipstick. The dipstick typically includes a blade portion that extends though a tubular guide into a fluid reservoir and includes markings thereon indicative of an amount of fluid within the reservoir. A handle is attached to the blade portion and seals against the tubular guide by way of threads and a compressible member such as an o-ring.
Although this type of fluid level gauge may be adequate for some systems, it can also be problematic. Specifically, if the tubular guide includes bends, the blade portion may bind against the tubular guide at the bends. This binding tends to resist rotation of the handle and, in some situations, can cause the blade to twist during engagement of the handle with the tubular guide. During subsequent operation, the twisted blade portion acts like a spring having stored energy, the stored energy working to disengage the handle from the tubular guide. If the handle disengages from the tubular guide, it may be possible for gases and/or fluid to pass to the atmosphere.
One system focused on reducing the likelihood of handle/guide disengagement is described in U.S. Pat. No. 5,485,681 (the '681 patent) issued to Hitchcock on Jan. 23, 1996. The '681 patent describes a swivel type dipstick with a screw-on cap. The swiveling motion allows the blade of the dipstick to rotate freely, thus allowing the dipstick to be used with nonlinear fill tubes. The screw-on cap provides a tight seal between the dipstick and the fill tube, thereby preventing fluid leakage.
The blade of the dipstick of the '681 patent is connected to the cap by way of a swivel. Specifically, the blade is rigidly connected to the swivel by a dowel, the swivel then being connected at an opposite end to the cap by a cylinder having a two-tined fork. Each of the tines terminates in a triangular grip. The tines are made out of a material such as plastic that is suitably resilient so that the tines may be bent inwardly. In their normal position the distance between the further most tips of the triangular grips is larger than the interior diameter of the cap. However, when the tines are bent inwardly, the distance between the furthermost tips of the triangular grips is smaller than the interior diameter of the cap, thus allowing the tines to be inserted into the cap. When the tines are then released, they expand outwardly to their normal position and engage the interior surface of the cap, thus securing the dipstick blade to the cap. However, since the tines only slidingly engage the interior surface of the cap, the dipstick blade rotates freely (i.e., swivels) around its longitudinal axis.
Although the dipstick of the '681 patent may help reduce the likelihood of unintentional cap/guide disengagement, it may still be suboptimal. That is, because the connection between the blade and the cap relies on the bending of plastic tines, the dipstick may be insufficiently robust. For example, it may be possible for the tines to lose their resiliency with time and fail to expand and engage the cap sufficiently. This loss of resiliency could result in the blade becoming detached from the cap. In addition, with the loss of resiliency, the plastic tines may become brittle and break, again resulting in the detachment of the blade from the cap. It may also be possible for the blade to become detached from the swivel if the dowel were to become dislodged therefrom by, for example, engine vibrations or during servicing.
The disclosed fluid level gauge is directed to addressing one or more of the issues set forth above.